In many applications, it is desirable to measure a variable, for example a current or a voltage, and to carry out open-loop or closed-loop control based on this measurement. One example of this is measuring a current in an electric motor, wherein the electric motor is in turn controlled on the basis of the current measurement. Another application is measuring currents in rectifiers, for example for solar cells. In such apparatuses, periodic control signals are used, for example for driving the motor or for controlling the rectification. These periodic control signals can cause periodic disturbances in signals to be measured, with the result that, for example in the case of a current or voltage measurement, a signal that is subject to a periodic disturbance is measured. For many applications, these periodic disturbances in the measured signal can be undesired. In addition to the periodic disturbances, it is also possible for individual peaks to occur in the measured signal, which are caused by the control signals and can likewise be undesired. In other applications, a signal of interest can also be superposed by periodic disturbances.
Various traditional solutions have various disadvantages, such as for example a sensitivity to voltage or current peaks or relatively high delays, wherein such high delays can result in instabilities for example in the case of control loops.
It is therefore an object of the present application to provide options for being able to measure a disturbed variable such as for example a current with as little delay as possible.